Combustion apparatus



Feb. 13, 1968 T, E, EMMERT 3,368,606

COMBUSTION Af-PARATUS Filed July 18, 1966 /26/36 ,a5 el@ 22 United States Patent O 3,368,606 COMBUSTION APPARATUS Thomas E. Emmert, Lebanon, Ind., assignor to Stewart- Warner Corporation, Chicago, Ill., a corporation of Virginia Filed July 18, 1966, Ser. No. 566,067 Claims. (Cl. 158-76) ABSTRACT 0F THE DTSCLGSURE The following specification describes a fuel burner in which the fuel ejected from a nozzle is mixed with swirling axially directed air and passed through axially aligned apertures spaced around the central opening of an air cone located in front of the nozzle to establish a stable flame in front of the nozzle.

This invention relates generally to a fuel burner assembly and more particularly to an air cone for use therewith.

It is well known in the art of heating commercial and residential buildings to use a gas or oil burning device in combination with a combustion chamber. Conventionally, a combustible fuel is supplied to the burner unit and mixed with air to thereby effect a combustion reaction within the combustion chamber. In utilizing a burner unit to introduce a combustible fuel, such as fuel oil, into the combustion chamber, it is of utmost importance that the fuel be properly mixed with air and ignited with the resulting flame front being properly controlled to maintain a highly eflicient exothermic reaction. It is a common practice to provide an air cone on the forward end of the burner tube to control the fiame front at the end of the burner in the combustion chamber. The specific configuration of the outlet orifice provided in the air cone is critical to a proper combustion flame, with an improper exit orifice causing either overfiring and waste in fuel, or underliring, resulting in substandard heating.

It is the primary object of the subject invention to provide an air cone for use in conjunction with a fuel burner, which air cone is effective in establishing a highly stable flame front thereby resulting in a highly efficient combustion reaction.

Another object of the present invention is to provide an air cone for use with a burner device, which air cone provides a novel means for introducing air into the combustion process to thereby substantially increase the overall efiiciency of the burner device.

It is a further object of the present invention to provide an improved air cone for use with a burner device, which air cone is provided with a central discharge orifice and a plurality of smaller orifices disposed about the central orifice to establish a luniform axial velocity of air flow in order to stabilize the iiame front during combustion.

Another object of the present invention is to provide an air cone which may be cooperatively associated with a fuel burner device to define a burner unit which is economical to manufacture and highly efficient in operation.

Further objects and advantages of the present invention, together with the organization and manner of operation thereof, may best be understood by reference to the following description taken in connection with the 3,368,606 Patented Feb. 13, 1968 ICC accompanying drawing, in the several figures of which like reference numerals identify like elements and in which:

FIGURE 1 is a side elevational view showing the air cone of the present invention mounted at the outer end of a burner device;

FIGURE 2 is a fragmentary vertical view, partly in section, showing the air cone of the present invention mounted in an operating position relative to a nozzle and electrode assembly; and Y FIGURE 3 is an end view of the air cone of FIG- URE 2.

Referring now to the drawing, there is shown in FIG- URE l a burner device, indicated generally by the reference numeral 10, Ahaving a burner housing 12 secured to a support frame member 14 by a plurality of support screws, one Iwhich is indicated at 16. An electric motor 18, which serves to drive a fuel pump and a combustion air fan located within the housing 12, is secured to the housing by means of a pair of support screws 20. A cover member 22 is suitably secured to the upper portion of the burner housing to enclose a primary control as embly and an ignition transformer (not shown) which control the discharge of a pair of electrodes 24 in a conventional manner.

A Igenerally cylindrical burner tube 26 is fixed to the burner housing 12 and projects in a horizontal position therefrom. The burner tube 26 is adapted to extend into a combustion chamber (not shown) in a conventional manner. The burner tube 26 has contained therein the above reference electrodes 24 and a nozzle line 28. The electrodes 24, which form part of electrode and buss bar assemblies 30, are electrically connected to the ignition transformer which in turn is connected to the primary control assembly, all in a conventional manner. The nozzle line 28 serves as a flow conduit for a combustible fuel, such as fuel oil, and has a nozzle adapter 34 aiiixed to the outer end thereof. A discharge nozzle 36 is secured to the outer end of the nozzle adapter 34 and has a discharge orifice for the combustible fuel.

A swirl disc or flame stabilizer 38 is positioned rearwardly from the discharge orifice of nozzle 36 and the electrodes 24 and comprises a disc having radially extending louvered portions therein. The swirl disc 38 serves to promote a swirling or turbulent action in air which is introduced into the internal bore 40 of burner tube 26 and is passed through the swirl disc into the forward section 4l of the burner tube. The swirling air thereupon intermixes with the fuel discharged from nozzle 36 to provide a combustible fuel-air mixture.

The above described burner housing 12, motor 18, cover member 22, burner tube 26, electrodes 24, fuel discharge nozzle 36, and swirl disc 38 are of conventional design and considered by themselves form no part of the present invention.

Referring now to FIGURES 2 and 3, an air cone, shown generally at 42, is secured to the outer end 44 of the burner tube 26 in a suitable manner, such as by screws 46. The air cone preferably has an inner end cylindrical collar portion 48 which snugly engages the outer end 44 of the burner tube 26.

The air cone 42 has an outer end portion 50 which lies in a plane normal to the longitudinal axis or center line of the cylindrical burner tube 26. The outer end portion 50 of the air cone 42 is spaced outwardly from the end 44 of the burner tube 26 and is inter-connected to the 3 collar portion 48 through an intermediate wall portion or` approach section 52, The configuration of the wall portion 52 is shown in FGURE 2 as being generally arcuate when viewed in cross-section along a plane passing through the center line of the burner tube 26, but may have any configuration which will provide a proper mixing of fuel and air and allow a smooth discharge of the resulting fuel-air mixture as will be described hereinbelow. Thus, the cross-sectional configuration of the wall portion 52 may take the form of a pure conical section as opposed to the generally radial arcuate section shown.

A central orifice 54 is provided in the o-uter end portion 50 of the air cone 42 `and forms the main discharge orice of the air cone. The discharge orifice 54 is circular, when viewed as in FIGURE 3, with its axis or center line being coincident with the longitudinal axis or center line of the burner tube 26. A plurality of smaller orifices 56 are provided inthe end portion 50 of the air cone 42 and are disposed in spaced circumferential relation about the central orifice 54. The small orifices S6 are of equal size and lie on a common circumference about the axis of the central orifice 54, radially equidistant therefrom. Noting FGURE 3, the small orifices 55 are also circular in configuration and have a diameter substantially less than the diameter of the orifice 54.

It is important that the fuel discharge nozzle 36 and the electrodes 24 be properly positioned in the burner tube 26. The position of the discharge nozzle 36 and the electrodes 24 relative to the end of the burner tube 26 will be dependent upon the particular size of the burner device used. Generally, the discharge nozzle 3d should be located Vfrom l/Q inch to 11/1@ inch from the end of the burner tube 26. In every case, the nozzle line 2S should be set in a position where the best performance is obtained and where there is no fuel impingement on the air cone 42. The ignition points of the electrodes 24 should be approximately /2 inch apart, with a inch clearance maintained between `the ignition points and the discharge nozzle 36. The ignition points should not extend more than 1,/16 inch ahead of and inch above the center line of the discharge nozzle. The swirl disc 38 is preferably positioned from 3 to 3% inches rearwardly of the vertical plane of the outer end of the discharge nozzle 36.

In operation, a combustible fuel, such as heating oil No. 2, Commercial Standard CS-12 Grade, is introduced into the nozzle line 2S and discharged through the orifice of discharge nozzle 36. Simultaneous with the discharge of combustible fuel from nozzle 36, air is impelled through the internal bore 40 of the burner tube 26 and passed through swirl disc 3S, thereby being caused to swirl in a turbulent manner in the forward section 41 of the burner tube adjacent the fuel discharge nozzle 36* As fuel is discharged from the nozzle 36, the primary control assembly effects energize-tion of the ignition transformer thereby causing an electrical discharge across the electrodes 24 whereupon the fuel emitted from discharge nozzle 36 is partially mixed with air and ignited. The primary control assembly effects de-energization of the ignition transformer upon complete ignition of the fuel emitted from the discharge nozzle 36, the period of ignition generally taking no longer than two minutes. The ignited fuel in admixture with the air passes through the central discharge orifice 54 and into the center of a cornbustion chamber (not shown) to effect an ex-othermic reaction within the combustion chamber in a conventional manner.

As the ignited fuel passes through the central orifice 54, swirliig air from the swirl disc 38 impinges upon the approach section S2 of the air cone 42 and passes through the small discharge orices 56 to the combustion chainber. The small orifices 56 establish therethrough a uniform axial velocity of air flow which stabilizes the flame front exteriorly of the burner tube. The fiame front is the point at which the combustion process becomes visiblethat is, the point in the profile of the combustible mixture where the rate of fiame propagation (upstream toward the air cone) matches the velocity of the mixture. t is highly desirable that this flame front be stable and reasonably well defined. The configuration of the approach section 52 relative to the plane of the orifices 54 and 56, and the size, number and location of the orifices, are related to the fuel input through the nozzle 36 and may be varied from one fuel input to another to obtain optimum performance. The use of an air cone 42 as described results in a more uniform combustion mixture, a reduction in combustion sound, and an increase in combustion efficiency,

While .a preferred embodiment of the present invention has been shown and described, it will be understood by those skilled in the art that various rearrangements and modifications may be made therein without departing from the spirit and scope of the invention` I claim:

1. For use with a fuel burner assembly including a burner tube and means for introducing combustible fuel into the burner tube and causing ignition thereof in the presence of air impelled therethrough, an air cone Securable to the outer end of the burner tube, said air cone including an inner end portion engaging the outer end of the burner tube and an outer end portion, said outer end portion having a central orifice there-in of a lesser cross-sectional area than that of the burner tube through which ignited fuel is adapted to pass, and said outer end portion having a plurality of smaller orices located solely in a radial plane relative the axis of said central orifice in spaced circumferential relation about said central orifice and radially equidistant therefrom through which a uniform axial velocity of air fiow is established to stabilize the ame front exteriorly of the burner tube during combustion of the combustible fuel.

2. The air cone defined in claim 1 wherein said central orifice and said plurality of smaller orifices are of circular configuration.

3. An air cone as defined in claim 1 including an annular arcuate portion intermediate said inner end portion or" said air cone and said outer end portion of said air cone, said annular arcuate portion terminating immediately adjacent said smaller orifices to thereby define an approach to said smaller orifices for introducing air therethrough.

4. For use with a fuel burner assembly including a burner tube and means for introducing combustible fuel into the lburner tube and causing ignition thereof in the presence of air impelled therethrough, an air cone securable to the outer end of the burner tube, said air cone including an inner end portion engaging the outer end of the lburner tube and an outer end portion, said outer end portion having a central orifice therein normal to the longitudinal axis of the burner tube of a lesser crosssectional area than that of the burner tube through which ignited fuel is adapted to pass, and said outer end portion having a plurality of smaller orifices disposed in a common plane with said central orifice normal to the longitudinal axis of said burner tube in spaced circumferential relation about said central orifice and radially equidistant therefrom through which a uniform axial velocity of air fiow is established to stabilize the flame front exteriorly of the burner tube during combustion of the combustible fuel.

5. For luse with a fuel burner assembly including a burner tube and means for introducing combustible fuel into the burner tube and causing ignition thereof in the presence of air impelled therethrough, an air cone securable to t-he outer end of the burner tube, said air cone including an inner end portion engaging the outer end of the burner tube and an outer end portion, said outer end portion having a circular central orifice therein normal to the longitudinal axis of said burner tube of a lesser cross-sectional area than that of the burner tube through which ignited fuel is adapted to pass, and

s e said outer end portion having a plurality of smaller cir- References Cited cular orices disposed in -a common plane with said cen- UNITED STATES PATENTS tral orifice normal to the longitudinal axis of said burner tube in spaced circumferential relation about said cen- 2568878 9/1951 W15 15S-"76 tral orlice and radially equidistant therefrom through 5 2676649 4/1954 Diehl et al' 158-76 which a uniform axial velocity 0f air flow is established to stabilize the flame front exteriorly of the burner tube FREDERICK L' MATTESON JR"P'lmary Examiner during combustion of the combustible fuel. E. G. FAVORS, Assistant Examiner. 

